<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
	<style type="text/css">
		#container {
			width: 960px;
			margin: 0 auto;
		}
		#container iframe {
			opacity: 0.5;
		}
	</style>
</head>
<body>
	<div id="container">
		<iframe src="http://www.jd.com" width="960" height="800"></iframe>
	</div>
	<textarea rows="10" cols="50"></textarea>
</body>
</html>